The annual data center energy consumption in the US is estimated to grow to over 100 billion kWh at a cost of $7.4 billion by 2011. Another trend analysis estimates by 2014, Infrastructure and Energy costs would contribute about 75% while IT would contribute a significantly smaller 25% towards the overall total cost of operating a data center. Increasing the actual amount of computing work completed in the data center relative to the amount of energy used, is an urgent need in the new green IT initiative.
Both server consolidation and server features like voltage and frequency scaling can have a significant effect on overall data center performance per watt. Server consolidation is based on the observation that many enterprise servers do not utilize the available server resources maximally all of the time, and virtualization technologies facilitate consolidation of several physical servers onto a single high end system for higher resource utilization. Modern server power control features like Dynamic voltage and frequency scaling (DVFS) drive the server performance approximating energy-proportional computing by adapting processor operating frequency (voltage) upon run-time workload. The problem to be solved is designing an efficient solution for managing a virtualized data center with reduced energy consumption by utilizing both cluster-level server on-off energy management, and local DVFS control for server-level energy management.
On server level power control, there are independent or cooperative DVFS techniques. On cluster level energy management, there are dynamic server/load consolidation methods. While the solutions at each level may be combined to run a virtualized data center, they may interfere with each other, and a arbitrary combination of two solutions do not necessarily utilize their full capability. No energy management solution is proposed to explicitly manage the two levels in a coordinated approach.